Haircutting device



ec. 2L i943. A. HoRowlTz ET AL 2,337,391 HAIR CUTTING DEVICE Filed March5, 1940 Patented Dec. 21, 1943 HAIRCUTTING DEVICE Alexandre Horowitz andAlexis hoven, Netherlands, assigno van Dam, Eindby mesne assignments, toHartford National Bank and Trust Company, Hartford, Conn., ApplicationMarch 5, 1940, Serial No.

as trustee In Germany February 21, 1939 claims. (ci. so-ia) Ourinvention relates to hair-cutting devices, particularly dry electricrazors, having a cutting or shear plate and a rotatable cutter which isusually electrically driven,

Although not limited thereto, our invention is particularly adapted foruse in hair-.cutting de vices of the type described in our co-pending U.S. patent application Ser. No. 276,746 led May 31, 1939.

In devices of the above type the cutter gener-A ally runs in a groove inthe shear plate and is confined to a fixed path. More particularly, thecutter may snugly' fit into the groove and be guided by the wallsthereof, or may be exactly centered in the groove, for instance by beingaccurately journalled on the shaft ofthe cutter or by being mounted on apin which is accurately journalled in the cutting plate. We have foundthat when such devices have been in service for some time. grooves maybe cut into one or both of the active surfaces of the cutter and shearplate. As a result the cutting action is deleteriously affected and inaddition the shear plate may be heated due to the high friction producedby the roughened surfaces, which is particularly disadvantageous becausethe shear plate comes in contact with the skin during operation.Furthermore, the friction of the roughened surfaces increases the loadon the motor and slows down the same.

The main object of our invention is to overcome the above difficultiesand for this purpose we make the groove slightly wider than the cutterand so mount the cutter that it will be guided solely by the walls ofthe groove. cutter has a small clearance,` for instance about 0.2 mm.,with the walls of the groove and is free to move over the entire cuttingsurface thereof.

The radial movement of the cutter is limited only by the Walls of thegroove and therefore the cutter will move with a combined radial andcircular motion over the entire surface of the plate. Consequently.there will be no grooving or erosionof the active surfaces and shearplate. Furthermore, after the device has been operated for a short timethe active surfaces take on a high polish which reduces the friction andconsequently the heating of the shear plate and the load on the motor.As a result the speed of the motor increases which improves the cuttingaction, and shorter cutting of the hair is obtained.

We prefer that the surfaces of the groove which guide the cutter, aswell as the corresponding surfaces of the cutter, make an angle of aboutThus, the.

of the cutter j with the active surface of the groove, so as to obtainan accurate guiding.

In one embodiment of the invention we resiliently mount the cutter andmake the depth ofv erence to the accompanying drawing in which thesingle figure is a sectionized side view of a portion of an electric dryrazor embodying the invention.

In the drawing, the reference numeral 9 indicates a housingof insulatingmaterial, such as Bakelite, in which's located an electric motor havinga shaft 1 provided at its end with a bore and a diametrical slot 6.Secured to the end of housing 9 by means of a screw collar 20 ofBakelite" is a cup-shaped metal shear plate 2l.

Shear plate 2 l is provided with a central cavity 22 and a plurality ofradially-extending narrow slits 2 which extend through the annular endportion. 'Ihe inner part of the annular portion is provided with anannular groove 25 having a width I2.

A hollow member I of insulating material has two projections Y twoprojections 23. A compression spring 8 has one end bearing on shaft 'land its other end bearing on the member 4 to forcethe latter upward. Theprojections 23 t into clearance holes in a cutter 3 having two engage'the bottom surface of groove 25.

The spring 8! serves to press the cutting edges Il against the shearplate 2| and a metal member i0 screwed into housing 9 serves to limitthe cutter 3 and for this purpose has its upper surface spaced adistance I1 from the lower surface of the cutter.

According to the invention the groove 25, which determines the activecutting surface, is so proportioned that the cutter 3 has a small playof, for example, 0.2 mm., in the radial direction. For this Purpose thewidth I2 ofthe groove 25 is made about 0.2 mm. greater centeredexclusively I5 of the groove 25,

The movable mounting of member 4 on shaft l cutting edges il which andwithin member I permits free radial movement of the cutter 3 within theentire groove 25 so that the bottom surface of the groove isautomatically maintained smooth, and heating. erosion or grooving of thecutting edge of the cutter and the bottom surface of the groove 25 isavoided.

To obtain an exact boundary of the active bottom surface of groove 25,it is advisable that the walls I4 and I5 as well as the cooperating endsurfaces of the cutter 3 extend perpendicular to the active bottomsurface of groove 25.

The depth I6 of groove 25 is preferably made greater than the distancethe cutter 3 can move in the axial direction, i. e. distance I1. Thisprevents the cutter 3 from leaving groove II under any condition, evenif the motor is removed.

As shown the shear plate I is stationary, but it may also be movable, asdescribed in our copending U. S. patent application S. N. 303,290, iiledNovember 7, 1939, now U. S. Patent No. 2,283,834, issued May 19, 1942.

Although we have reference to specic examples and applications, we donot desire to be limited thereto because obvious modifications willpresent themselves to one skilled in the art..

What we claim is:

1. In a hair-cutting device, a shear plate provided with a groove havingan active cutting surface and guiding surfaces, a member having acutting portion running within said groove, said cutting portion havinga, clearance of the order of 0.2 mm. with said guiding surfaces of thegroove, a driving means, and a coupler member loosely connecting saidcutter member to said driving means allowing free movement of the cuttermember between said guiding surfaces. n

2. In a hair-cutting device, a shear plate provided with an annulargroove having an active cutting surface and guiding surfaces, a memberhaving a cutting portion running within said groove and being rotatablydriven, said cutting portion having a width of the order of 0.2 mm. lessthan the distance between said guiding surfaces, a driving means, and a,coupler member loosely connecting said cutter member to said describedour invention with driving means allowing free radial movement of thecutting portion between the guiding surfaces of the grooves.

3. In a hair-cutting device, a shear plate provided with a groove havingan active cutting surface and guiding surfaces substantiallyperpendicular thereto, amember having a cutting portion running withinsaid groove and having surfaces parallel to said guiding surfaces thedistance between said latter surfaces being of the order 0f 0.2 mm. lessthan the distance between the guiding surfaces, a driving means, and acoupler member loosely connecting said cutter member to said drivingmeans allowing free movement of the cutting portion between the guidingsurfaces.

4. In a hair-cutting device, a shear plate provided with a groove havingan active cutting surface and guiding surfaces, a member having acutting portion running within said groove, said cutting portion havinga clearance of the order of 0.2 mm., withsaid guiding surfaces, adriving means, and a coupler member loosely connecting said cuttermember to said driving means allowing free movement of the cutter memberbetween the guiding surfaces, resilient means pressing thecuttingportion against the active surface of the shear plate while permittingmovement in a direction perpendicular thereto, and means to restrictsaid movement to a distance less than the depth of the groove.

5. In a hair-cutting device, a shear plate provided with an annulargroove having a radially extending active cutting surface and guidingsurfaces perpendicular to said cutting surface, a rotatable memberhaving a cutting portion running within said groove engaging the cuttingsurface thereof and having -a radial clearance of the order of 0.2 mm.with said guiding surfaces, a driving means, and a coupler memberloosely connecting said cutter member to said driving means allowingfree radial movement of said cutting portionwithin the annular groovelimited by the said guiding surfaces thereof.

ALEXANDRE HOROWITZ. ALEXIS VAN DAM.

